Self-Organising Agro-Ecosystems

209 Pages·2009·1.96 MB·English

Self-organising Agro-

ecosystems
by
Raoul A. Robinson
Second edition, revised
Sharebooks Publishing
www.sharebooks.ca
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© Raoul A. Robinson, 1996, 2004, 2007.
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Library and Archives Canada Cataloguing in Publication
Robinson, Raoul A.
Self-organising agro-ecosystems / by Raoul A. Robinson. -- 2nd ed.,
rev.
Also available in electronic format.
Includes bibliographical references.
ISBN 978-0-9783634-1-3
1. Agricultural ecology. I. Title.
S589.7.R63 2007 577.5'5
C2007-905616-4
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Preface
This work proposes methods of reducing, even eliminating, the use of crop protection chemicals from our
crops and environment. It seems that this can best be achieved by self-organisation (sensu Adam Smith) within
agro-ecosystems. This self-organisation can be brought about by numerous plant breeding clubs that are employing
durable resistance to crop parasites.
If we consider the food production of a country, we find a self-organising system. Many farmers, acting
individually, choose what crops to grow, and what cultivars of those crops to grow. Their decisions are based
mainly on their environment, and on market demand, which comes from the decisions of individual merchants who
buy their produce. Systems of transport and food processing convert raw materials into marketable products, and
retailers make these products available to consumers through stores and super-markets. These consumers choose
what they buy, usually on a basis of either cost or quality. The stores must stock items according to customer
preferences. There must be some government control to ensure purity and hygiene, and to prevent monopolies and
cornered markets. But, in general, too much government control is damaging. This was revealed dramatically by
the failure of the Soviet system of State-controlled agriculture. Government control must be kept to the essential
minimum, and the entire system should be self-organising. The importance of this phenomenon of self-organisation
was first recognised by Adam Smith (1723-1790) in his book The Wealth of Nations, published in 1776, although
he did not use this term. Immanuel Kant (1724-1804) was apparently the first to use the term ‘self-organisation’.
The present volume is intended primarily for universities wishing to initiate student clubs for plant breeding, but it
may also be of interest to any scientist involved with crop parasites. A proper understanding of this topic requires
an acquaintance with the general systems theory, modern complexity theory and, most of all, various concepts of
the ecosystem and the pathosystem.
A further purpose of the present book is to summarise, bring up to date, and present in one volume,
concepts that I consider relevant in earlier writings of mine, including books that are now out of print.
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Chapter One
1. General Systems Theory
1.1 Introduction
The founder of systems theory was a little known Russian scientist called Alexander Bogdanov, who
published a three-volume work entitled Tektology in 1912-1917. A German edition was published in 1928 but the
work remained largely unrecognised and unknown in the West. Lenin denounced Bogdanov on ideological
grounds, and the Soviet authorities suppressed his works.
About a quarter of a century later, an Austrian scientist, Ludwig von Bertalanffy, developed his general
systems theory. It is unlikely that he was ignorant of Bogdanov’s earlier work, but he never acknowledged it, and
the lingering possibility of plagiarism cannot be entirely dispelled. Nevertheless, Bertalanffy was very influential,
and he is widely recognised as one of the principle founders of the general systems theory. His main contribution
was the concept of the open system, which would allow energy to flow into it and, interestingly, this was an
enlargement of the second law of thermodynamics.
The French physicist Sadi Carnot first formulated the second law of thermodynamics, which postulates
that all energy gradients disappear in a closed system. This process is described as an increase in entropy, or
disorder. A closed system will thus tend to total internal uniformity of energy distribution. The open system is in
direct contrast and, by absorbing energy from outside, it can increase its energy gradients. An open system can be
described by saying that its negative entropy (negentropy) increases.
The concept of negative entropy can be applied to complexity of organisation, as well as to energy. In a
closed system, organisation tends to disappear, resulting in total disorganisation, and simplicity of arrangement. In
an open system, organisation tends to increase, resulting in complexity of organisation. All living systems are open
systems. They absorb energy, and their complexity of organisation increases.
1.2 Patterns
A pattern is an arrangement of units. A wall is a pattern of bricks, a word is a pattern of letters, a tune is a
pattern of notes, a molecule is a pattern of atoms, and so on.
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1.3 Systems
A system is a series of patterns of patterns, and each pattern of patterns is called a systems level (see 1.4).
There are many kinds of system, including electrical systems, mechanical systems, political systems, solar systems,
living systems, taxonomic systems, traffic systems, and so on. Systems theory studies the properties that these
various systems have in common. The most relevant of these properties are described under the various headings
below.
When it is applied to a word, the suffix ‘-ation’ often implies a system. Thus, we have ‘transport’ and
‘transportation’. When someone offers a ride and says “May I offer you transportation?” he should really say
‘transport’. And the system of public busses and underground trains in London is called “London Transport”, when
it should really be “London Transportation”. Similar comments can be made about ornament and ornamentation (a
system of ornaments), classification (a system of classes), experimentation, hyphenation, organisation, plantation,
medication, and so on.
1.4 Systems Levels
A pattern of patterns is usually called a systems level. For example, a book is a static system, which
consists of subsystems called chapters. Collectively, these chapters constitute a systems level. Each chapter
consists of subordinate patterns of patterns (or secondary subsystems) called paragraphs. And so on, downwards,
through sentences, words, and letters. The book itself is part of a super-system called a library. Clearly, a book has
many systems levels.
The importance of recognising systems levels is that they lead to the concepts of emergents, reductionism,
and suboptimisation. It will transpire that these concepts are central to any analysis of twentieth century crop
science.
1.5 Hierarchies and Networks
We tend to think of systems levels in terms of hierarchies. Each systems level is a rank in the hierarchy,
superior to the rank below it, and inferior to the rank above it. This is a very convenient and useful method of
analysis but, in fact, it is often a misrepresentation. It is perhaps more accurate to think in terms of networks, and of
networks nesting within other networks, all interacting within themselves and among themselves. Some networks
are larger than others, but this does not necessarily make them superior. Nevertheless, for simplicity of discussion, I
will continue writing in terms of systems levels.
A beautiful example of a network is the Internet. Here is a network of networks if ever there was one.
Perhaps we should think of the Internet as some kind of ‘super-organism’, with a ‘life’ of its own, and soon to
produce entirely new emergents (see 1.9) of enormous importance, which we can now perceive only dimly, if at all.
One of the more obvious emergents will be entirely new forms of global awareness and democracy.
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1.6 Homeostasis
The term ‘homeostasis’ was coined by the American physiologist Walter Cannon (1932) who was
describing the many self-regulatory mechanisms in the human body. The classic example of homeostasis is the
maintenance of body temperature. If we get too hot, we sweat, and evaporation cools us down. Conversely, if we
get too cold, we start shivering, and this involuntary exercise warms us up. Subsequently, homeostasis was
recognised in many other systems. For example, Lerner (1954), coined the term ‘genetic homeostasis’ to describe
the maintenance of an optimum genetic constitution of a population.
Homeostasis describes an important aspect of systems control, which results in the maintenance of a
desirable steady state. The mechanism of this control is called feedback.
1.7 Feedback
The term ‘feedback’ refers to the output controlling or influencing the input. The cyberneticists, who
recognised two kinds of feedback, introduced the concept of the ‘feedback loop’. And they called self-balancing
feedback ‘negative feedback’, and self-reinforcing feedback ‘positive feedback’.
Negative feedback is illustrated by all homeostatic mechanisms. For example, the automatic steering of a
ship exhibits a phenomenon that engineers call ‘hunting’. That is, the ship tends to veer slightly away from its
proper course, and the homeostatic steering mechanism brings it back again. But it may then veer slightly off
course in the other direction, and the steering mechanism brings it back again. This control, this homeostasis, which
returns the ship to its optimum, is negative feedback which, obviously, is self-balancing and valuable.
The resilience, flexibility, and overall stability of a complex adaptive system, such as an ecosystem, are a
consequence of its many negative feedback loops. For example, if a parasite becomes excessively damaging, the
host population accumulates resistance to it, and the parasitism returns to its normal level. It is this feedback which
brings the system back to its optimum whenever there is a deviation from the norm.
Positive feedback, being self-reinforcing, is often destructive. In common usage, it is often called a vicious
spiral. With positive feedback, there is an exponential increase. That is, the rate of increase is itself increasing.
An example of positive feedback is the self-fulfilling prophecy. If false rumours circulate that an airline is
about to go bankrupt, passengers will avoid it for fear of cancelled flights and valueless tickets. There is then a
rapid loss of business, which leads to increasingly strong rumours of bankruptcy. These increasing rumours are
positive feedback, and the previously solvent airline loses so much business that it may well go bankrupt. A similar
positive feedback can lead to a stock market crash. Another example is the ear-splitting howl that often develops in
a public address system. The microphone picks up the hum of the speakers. The hum is then amplified, and the
hum of the speakers increases. Positive feedback makes the hum rapidly louder and louder.
Perhaps the most important example of positive feedback in biology is the population explosion. The total
reproduction of a population depends on numbers of individuals. As reproduction increases, so numbers increase,
and the rate of increase itself increases, in a vicious spiral. Species that are capable of very rapid population
explosions are called r-strategists (see 1.13) and they are of special significance in crop pathosystems.
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1.8 Resilience
The combination of all the homeostatic mechanisms in a system produces the emergent property of
resilience. Resilience means that the system can suffer quite wide swings away from its optimum, and then recover.
1.9 Emergents
An essential feature of a pattern is that it has emergent properties, often called ‘emergents’. An emergent
can be observed only at its own systems level. It cannot be discerned from any lower systems level. This can be put
another way by saying that an emergent has ‘novelty’. That is, as one progresses to higher and higher systems
levels, each emergent is new in the sense that it does not occur at any lower systems level. An emergent is often
described by saying that the whole is greater than the sum of its parts. The whole includes both the sum of all the
parts of the system, as well as the emergents, which are additional to the sum of all those parts.
In a living system, any behaviour, at any systems level, is an emergent property of that system. Life itself
is an emergent. In the past, various characteristics that are unique to living organisms were often described as ‘vital
forces’, and these too are emergents. So too are the various human intangibles, such as creativity, generosity, and
sociability, that are generally considered ‘unscientific’, simply because they cannot be easily measured.
In this general context of behaviour being an emergent, it is possible to speak of ‘plant behaviour’, at any
systems level. Obviously, plants do not walk and talk, but they exhibit behaviour in the sense of growth, sexual
recombination, reproduction, and death. Indeed, Fisher & Hollingdale (1987) have shown that plants with sun-
tracking leaves have both a primitive sight, and a daily movement. They also have a primitive memory that enables
them to turn their leaves, during the night, to face the rising sun.
At the higher systems levels, we can speak of ‘ecosystem behaviour’, and ‘pathosystem behaviour’. In
terms of the present book, the most prominent example of a pathosystem emergent is the system of locking that
emanates from the gene-for-gene relationship (see 4.14 & 4.15). This emergent cannot be seen from any lower
systems level and it has been scientifically ignored for this reason. Such blindness is called suboptimisation (see
1.11), and it is a consequence of reductionism (see 1.10). This topic is discussed in greater detail below (see 2.3).
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1.10 Reductionism
The term reductionism has two rather different meanings in science. One is laudable and the other is
derogatory. In its laudable sense, reductionism means a search for genuine fundamentals, which can occur at any
systems level. Less laudably, and in the terminology of systems theory, reductionism means working at the lower
systems levels. This is sometimes called the merological approach. However, it is not true fundamentalism. The
lower systems levels are not necessarily more fundamental than any other systems level. It is in this derogatory
sense that the term ‘reductionism’ is used throughout this book. In this sense of the term, reductionism is
hazardous, because emergents that are apparent only at the higher systems levels are invisible to investigators who
are working exclusively at the lower systems levels.
The converse of derogatory reductionism involves the higher systems levels, and it is called ‘holism’ or
the ‘holistic approach’. Excessive reductionism, and excessive holism, lead to biased science. Good science treats
all systems levels as being equally worthy of investigation.
It is often argued that the finer the details, or the lower the systems level, of the analysis, the more
fundamental the science becomes. Hence, the importance of particle physics. Hence, too, is a widespread love of
reductionism. It is not my intention to denigrate research conducted at the lower systems levels. However, far too
many scientific investigations are conducted exclusively at the lower systems levels. And I believe it is self-evident
that science must treat all systems levels with equal respect.
Taxonomists are often divided into so-called ‘splitters’ and ‘lumpers’. Splitters are reductionists, and
lumpers are holistic. For example, in the taxonomy of Citrus, Tanaka (1954), a splitter, proposed 145 species, while
Swingle (1967), a lumper, proposed only sixteen species.
Let us consider reductionism within the discipline of plant pathology. In the middle of the twentieth
century, plant pathology was almost exclusively concerned with the functioning of the gene-for-gene relationship
(see 4) at the systems level of the individual. That is, at the systems level of one individual host interacting with
one individual pathogen. Typically, a single detached leaf or leaf-disk would be inoculated with a single spore, and
the interaction would be qualitative. There would either be disease, or no disease. The pathologists would then
assemble a set of host differentials that would identify any ‘physiologic race’ of the pathogen. And they would
assemble a set of ‘physiologic races’, or pathogen differentials, that would identify any resistance. These
differentials became an essential tool of plant breeders who were working with this kind of resistance.
Then, for the next two or three decades, mainstream plant pathology moved to a lower systems level, and
concentrated on the individual resistance mechanism. In particular, it was concerned with the chemistry of these
mechanisms. This was known as ‘physiologic’ plant pathology and, for some thirty years, it claimed the lion’s
share of research funds. More recently, almost the entire discipline has moved to an even lower system level and it
has embraced molecular biology. This is the lowest systems level of all in biology. Indeed, it is impossible to go
any lower, because anyone who works at a lower systems level stops being a biologist and becomes a chemist.
Mid-century plant pathologists could and should have considered the converse trend, the holistic
approach, which involves the higher systems levels. The level above the individual host and the individual
pathogen involves the interaction of two populations. That is, the pathogen population and the host population
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interacting with each other. This is the level of the pathosystem. A still higher level is the ecosystem, which
involves populations of many different species interacting with each other and their environment.
It is important not to belittle or to over-emphasise the significance of any systems level. They are all
important, and a good scientist considers them all equally. What is dangerous, however, is the tendency to
exclusiveness, the tendency to claim that the systems level of one’s choice is uniquely important.
The importance of the holistic approach is that it does not suboptimise (see 1.11). It does not attempt to
analyse or to control the entire system in terms of only one or a few subsystems. Nor does it neglect the emergents
of the higher systems levels, which are undetectable at lower systems levels. There is no escaping the fact that
modern crop protection is in a mess. And, it seems, this mess is the result of reductionism and suboptimisation.
1.11 Suboptimisation
Suboptimisation means that a system is being analysed or managed at too low a systems level. In systems
analysis, suboptimisation leads to false conclusions. In systems management, it leads to material damage to the
system. Suboptimisation is the equivalent of “not seeing the forest for the trees” or “arguing from the particular to
the general”. It will transpire that, in the analysis and management of our crop pathosystems, we have been
suboptimising to an incredible extent, for the whole of the twentieth century. And our crop pathosystems have been
damaged accordingly.
A simple example of suboptimisation comes from considering the systems levels of a book. Consider a
Shakespeare play, and the personality of, say, Hamlet. This personality is an emergent. It is so complex that every
great actor can have a different, although valid, interpretation of it. But the personality of Hamlet is discernible
only in terms of the play as a whole. If that personality is examined in terms of only one act, one scene, one speech,
one sentence, or one word, the examination will become increasingly incomplete, and increasingly inadequate.
Suboptimisation results from two distinct factors. The first, and most important, is that emergents can be
discerned only at their own systems levels. An emergent cannot be discerned from lower systems levels. The
personality of Hamlet is an emergent from the play as a whole. Anyone who studies that personality from only one
subsystem cannot see the entire personality, and will inevitably suboptimise, reaching inadequate, and false,
conclusions concerning it. The second factor contributing to suboptimisation is that other subsystems tend to be
ignored and neglected. Inevitably, the systems analysis is then incomplete and inaccurate. And the systems
management is inappropriate.
Two examples will illustrate the importance of these points. Richard Dawkins (1976), in a popular book
called The Selfish Gene, produced what must surely be the ultimate suboptimisation, the extreme of reductionism.
He attempts, light-heartedly no doubt, to explain the evolutionary emergents of the most complex living organisms
in terms of the ‘selfish gene’. This sub-optimisation approximates to the sub-optimisation of explaining the
character of Hamlet in terms of a single letter of the alphabet.
At the opposite extreme, Vernadsky (1926), working at the highest systems level, developed the concept
of the biosphere, but his work was largely ignored in the West. Then James Lovelock (1972) suggested that the
entire biosphere was a single, self-organising system. He called this idea The Gaia Hypothesis. At the time, most
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scientists rejected his idea out of hand. But Lovelock is undoubtedly right, and his idea has already had a profound
influence on the life sciences. It is also an emergent that was previously unobserved, because no one was working
at that high a systems level, and the extraordinary beauty of our planet, when seen from space, was then quite new.
A lot of suboptimisation has occurred in crop science because of too much specialisation, and too many
‘water-tight’ compartments. Crop science has been divided into the principle schools of genetics, pathology,
entomology, pedology horticulture, and agronomy, and each school usually became a separate research or
university department, often isolated in its own building. The members of one school rarely spoke to the members
of the other schools, or to related schools, such as ecology, systems theory, and evolutionary biology. Possibly the
worst example of suboptimisation in crop science involved the misuse of the vertical subsystem (see 5.3). In fact,
most of our studies of the crop pathosystem during the twentieth century have been distorted by suboptimisation.
As a consequence, the crop pathosystem has been seriously mismanaged, and this is why we now use crop
protection chemicals costing billions of dollars a year, and suffer pre-harvest crop losses of up to 25% (Pimental et
al, 1993) in spite of the use of these expensive and hazardous chemicals.
1.12 Local Optimisation
In a balanced ecosystem, every variable is at its optimum. Attempts to maximise any of these variables
will lead to an unbalanced system, even to the point of irreversible damage or self-destruction. However, it could
be argued that this kind of suboptimisation is exactly what has occurred in the agro-ecosystem and, at this point, it
is necessary to distinguish between suboptimisation and local optimisation.
Local optimisation means that a variable is changed to suit new circumstances resulting from the fact that
the system itself has been changed. An obvious example is the yield and quality of a domesticated crop species,
compared with its wild progenitors. The domesticated species is a component of an agro-ecosystem, not a wild
ecosystem. The chief requirement of a wild ecosystem is survival in the face of ecological and evolutionary
competition. In the agro-ecosystem, this competition has been largely eliminated. The survival of the cultivar
depends on entirely new criteria, such as its yield and the quality of its product. The increase in these properties is
local optimisation. This increase would be suboptimisation in a wild ecosystem, but the agro-ecosystem is a
different system, with different requirements.
If all people disappeared, and all agriculture stopped, the agricultural lands of our planet would quickly
revert to being wild ecosystems, and our domesticated species would soon disappear. Typically, the most highly
domesticated lines would disappear first, and the least domesticated lines would survive the longest.
In a later section of this book (see 11.10), the domestication of horizontal resistance to crop parasites is
discussed. This quantitative resistance occurs in every plant and against every parasite of that plant. Its natural
optimum is sufficient to ensure that the parasites of a wild host plant do not impair its competitive ability. However,
this kind of resistance is at a low level in most modern cultivars. Indeed, it is often at a level considerably lower than
that of the optimum in wild plants. We should now domesticate it to a considerably higher level than the optimum of
wild plants, if we want to reduce the use of crop protection chemicals to the minimum. This domestication of
horizontal resistance would constitute local optimisation.
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